The lens within the human eye has the capability of changing shape and thereby focus so that objects both far and near can be registered sharply on the retina. This ability to change focus is known as accommodation. With age, the lens gradually loses its range of accommodation. The human lens not only loses accommodative range with aging, but also transparency. When the lens loses a significant amount of transparency (thus producing a blurry image on the retina), it is said that the lens is cataractous or has become a cataract. Treatment for a cataract requires the surgical removal of the cataract and the placing of a man made synthetic lens (intraocular lens or IOL) in the eye. The earlier IOL's had a fixed focus and thus had no accommodative function.
However, in time a number of IOL's were designed in multifocal form. Different zones of a multifocal IOL have different dioptric powers. With such multifocal IOL's, light from objects, only within a specific range of viewing distances, passing through a particular zone will form sharply focused images on the retina. On the other hand, if an object is outside this range, its image formed by the zone under consideration will be blurry. Multifocal IOL's typically have two or more zones, each designed for a specific viewing distance. A consequence of this design approach is that the imagery of multifocal IOL's is never very sharp. The success of multifocal IOL's depends on the visual processing system of the patient's eye and brain that tends to pay attention to the light most sharply focused on the retina, and tends to ignore the light formed diffusely on the retina.
These were followed by IOL's that could move back and forth via ciliary muscle contraction and thus focus objects from different distances onto the retina. However, these IOL's have limited range of movement and thus a limited accommodative range.
Another form of IOL is made of an elastomer filled flexible balloon which is placed within the emptied lens capsule and alters lens shape under the influence of the ciliary muscle contraction.
Another accommodative IOL design is comprised of two positive lens elements (i.e. two plano-convex lenses) connected by two flexible hinges. The lens components are spread or come together in response to ciliary muscle contraction.
In our invention, we have an intraocular lens that preferably has an integral frame that enclosed at least 25% of the outer circumference of the lens i.e. 90° out of 360° of a circular lens.
Also we have an accommodative IOL that can be used alone or can be a combination of a positive lens (i.e. lens is thicker at center than at edge), and a negative lens (i.e. lens is thinner at center than at edge). Also, our IOL can alter dioptric power if placed in either of two intra ocular locations: a) within the capsular bag, or b) placed within the ciliary sulcus. In both locations, the contraction of the ciliary muscle alters the position of the lens.